Hi,
I’m trying to get my analysis from a downloaded extract to match with the results from the online tool for IPUMS USA 1850-2023. I get exact matches except for 1970.
While downloading the extract, I’m going with the default 1% metro fm1 and 1% metro fm2.
Should I be using some other sample to get my 1970 results to match with the query tool?
Thanks!
When selecting samples to analyze online, we note that the “U.S. file includes the single-year ACS samples and 1% versions of each decennial census, including the 1970 Form 1 metro sample.” Upon review, this appears to be incorrect; the USA 1850-2023 sample defaults to the Form 2 metro sample for 1970. Thank you for bringing this to our attention with your question.
You should find that the data match when comparing your online tabulation with the 1970 1% fm2 metro data. While you may combine multiple 1970 samples together (such as both metro samples) for analysis in your stats package, you should be aware that there are a number of questions that appear on one form but not the other. Additionally, since the person-level weight PERWT sums to the total US population within each sample, combining multiple samples from the same year causes PERWT to sum to multiples of the total population. For this reason, it’s necessary to divide all values of PERWT by the total number of samples from the same year in your analysis (e.g., divide by two if including both 1970 metro samples).